Thanks for the advice. If possible, I would like to get the sport pack one! Though I have heard that the front undertray can ground on speedbumps, which is a bit worrying as i live in europes largest speedbump - London!
I have found one which looks a little too good to be true, so chances are it is!
It is a 2.0 with 72,000 miles, teledial wheels, carbon fibre dials and sports seats (So i wonder if its a sport pack mode?), and he says cambelt + rollers changed, though i forgot to ask when and what mileage.
However, he says that he has been told that the throttle body needs to be changed. He says on idle, the revs go up and down, and it doesnt go past about 70ish miles per hour. I will speak to a friend of mine, and see if this is likely).
But for £700, with MOT until March, and Tax until september, doesnt seem too bad at all. he says its in excellant condition! (no leather seats though which is a shame)
To be honest, most of the 156's have lost their undertrays already mate, due to it scraping along one bump or another.
What year is the car? If it's older than 2000 and has black speedo dials as opposed to white, then it's a Sport Pack. All of the sports pack models came with 16" Tele-dial wheels, side skirts and black speedo dials. (They also ALL came with better suspension, but this isn't that noticeable)
The sport pack series came with either leather or Recaro seats, the Recaro's are actually better than leather I'd say, I'd love a set. They are grey and shaped very oddly, with sharp angles jutting out all over the place, cracking looking seats mind. If yours has those then it's an SP1 as SP2 and 3's came with leather as far as I'm aware.
Make sure it's not a bog standard 156 tarted up to look like a Sport Pack though, as you'll get worse handling if it is. Black dials is the thing to go for as that SHOULD indicate a true SP, that and the side skirts and Tele's.
From the sounds of it though it is an SP.
As far as the throttle body problem is concerned, I'm no mechanic and couldn't say for definite that's what's causing the problems. It sounds like it could be a dodgy MAF sensor? If that's the case you can pick one up for a 2 Litre TS for about £50 and fit it yourself easily enough.
Someone more technically minded will be along to correct me though I'm sure,
These cars are worth quite alot in parts alone mate, so even if it's buggered you'll still see £700 for parts EASY I reckon.
What colour is the car out of interest?